A front desk clerk at the Hampton Inn and Suites in Alameda, Calif. got a phone call from a man screaming into the phone Thursday morning, sources told NBCBayArea. The clerk could make out a few key words, including "American Airlines," "Flight 24" and "hijack." The clerk immediately called police and the police informed airport officials.

Justin Martin, a shuttle driver at the Hampton Inn in Alameda, said the clerk who answered the call didn't take the threat seriously until discovering online that the American Airlines jet was about to take off.

Martin spoke to the clerk just after the call came in around 9 a.m. Thursday.

The caller ranted in broken English that American Airlines Flight 24 was going to be hijacked while voices in the background yelled "(expletive) America" and "Allah is God," Martin said.

Within minutes, the plane was sent to a remote area of the San Fransisco International Airport tarmac, where it stayed for two hours. Passengers were evacuated and taken back to the terminal where they had to go through security screening again.

Police took a man and a woman from the back row of the plane into custody and questioned them but determined they were not connected to the alleged threat so they were released.

The plane was heading to JFK International Airport.There were 163 passengers and 11 crew members aboard the Boeing 767, American Airlines spokesman Tim Smith said. The plane was allowed to leave SFO just before 3 p.m. without any passengers.

Martin said he did not know why authorities detained a couple on the plane. The young man and woman were later released and said they were told by authorities they had been selected at random.

The clerk initially thought the callers were kids playing a prank, but Martin said he looked up the flight on the Internet and saw the plane was still on the ground after its original 7:30 a.m. departure was delayed.

That's when he and the clerk decided to take the threat seriously, Martin said.

"If something had gone down and we didn't do anything, that would have been a hell of a lot on our conscience," he said. "Whoever made this call needs to be busted."

Some of the passengers were still in San Francisco Friday morning awaiting flights to continue their travels.

A passenger on the flight said yesterday that two people on the plane were taken away in handcuffs. Michael Kidd told The Associated Press he saw uniformed police officers handcuffing a young man and a young woman sitting in the back row. They were taken off the plane.

But a fellow passenger suggested the couple may have been targeted because of their appearance. Michael Anderson, 20, said he remembered seeing the couple as he was checking in for the flight to New York's John F. Kennedy International Airport and saw them carrying passports from Pakistan.

"It definitely seems like it was racial profiling, based on what they look like physically and the fact they are Pakistani. It seems like this was a false accusation," said Anderson, a Yale University sophomore who was heading back to school.

The couple declined to discuss the possibility that they may have been targeted because of their appearance. "Of course we're upset, but I guess we can't blame them," the woman told the AP. "They're just doing their job."

Kidd said he and his wife did not believe the couple had been racially profiled based on appearances alone. The man wore a Los Angeles Lakers jersey and the woman was wearing a beret, and they looked like typical Californians, he said.

FBI sources told NBCNewYork that no one had been arrested and the feds were simply taking people off the plane two by two, bringing them to a private room and interviewing them.

"The two passengers were taken off the plane separately, but we cannot discuss the specifics why," said FBI spokesman Joseph Schadler.